Apparatus for drying materials by heat radiation



y 24, 1955 A. HALTMEIER 2,708,794

APPARATUS FOR DRYING MATERIALS BY HEAT RADIATION Filed March 26, 1952 F/GZ SECTION a-b INVENTOR. ALFRED HALTMEIER A T TORNE Y United States Patent APPARATUS FOR DRYING PJATERIALS BY HEAT RADIATION Alfred Haltmeier, Leverkusen-Bayerwerlr, Germany, as-

signor to Farbentiabriken Bayer Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany Application March 26, 1952, Serial No. 278,700 Claims priority, application Germany April 2, 1951 1 Claim. (Cl. 34-92) The present invention relates to apparatus for drying materials by heat radiation.

In my co-pending application Ser. No. 200,519 I have described an apparatus for'the drying in vacuo of wet material distributed in a thin layer on a moving belt. Drying is effected by means of radiating surfaces, preferably U-shaped radiating pipes, which are extended outwardly through the wall of an evacuated drying chamber by means of elastic expansion compensators, for instance expansion pipes. Because of the larger diameter of such expansion compensators, difiiculties are encountered in placing them in the upper section of the drying chamber when a large number of radiating pipes are installed side by side in close adjacency to one another. Consequently, the compensators had to be arranged in a staggered position.

In accordance with the present invention, an improved arrangement of the radiating pipes is achieved by providing slits in the upper section of the drying chamber transverse to the axis of the chamber, the boundary edges of the slits supporting boxes through the tops of which are led the arms of the radiating pipes. The passages in the tops of the boxes through which the upwardly directed arms of the radiating pipes are extended are closed with an air-tight seal. The boxes may be strengthened against compression due to external atmospheric pres sure by means of stiffening members provided between the radiating pipes. The walls of the drying chamber are advantageously protected from the heat of the radiating pipes by screens. The radiating pipes are, of course. made of corrosion-resistant material. However, the boxes may be constructed of another material if the upwardly directed arms of the radiating pipes are provided, closely above the U-curves, with cover plates which overlap one another like scales. The cover plates thereupon retain the rust particles which drop off the walls of the boxes and thus prevent these particles from being deposited on the belt drier. In order to utilize the width of the boxes for taking up the thermal expansion of the radiating pipes in the best possible manner, the upwardly directed arms of the radiating pipes are arranged, when cold or when the drying apparatus is inoperative, with a smaller clearance between the inner surface of the arm of the U and the box walls than between the outer surface of the U and the box walls.

In the accompanying diagramamtic drawing which illustrates one embodiment of the invention by way of example:

Fig. 1 is a longitudinal sectional view, and

Fig. 2 a cross-sectional view of a drying apparatus.

The drier comprises a belt 1 in a drying chamber 2. The chamber is provided with material feeding means 3 provided with a seal 5 and a dried material receiver 18. A screen 29 is located above U-shaped heat radiating pipes 15 and protects the wall of the chamber from radiation. The arms of the radiating pipes are directed upwardly and are led through the slits 74 and 75 in the upper section of the wall of the drying chamber 2. The radiating pipes project outwardly through the tops of the boxes 76 and 77 arranged above the slits 74 and 75. The radiating pipes are positioned close to the box walls 78 and 79 when they are cold. However, when the temperature is increased, thermal expansion causes these pipes to be displaced away from the walls 78 and 79. The boxes 76 and 77 are protected against compression by external atmospheric pressure by means of inner ribs 80.

In order to prevent the boxes 76 and 77 from being overheated by radiation emitted from the upwardly directed arms of the radiating pipes, radiation protective screens 81 are arranged between the radiating pipes and the walls of the boxes. The radiating pipes are made of corrosion-resistant material or at least provided with a corrosion-resistant surface. The boxes, however, may be constructed of ordinary iron if care is taken that any rust falling off is not deposited upon the moving belt; for this purpose, cover plates 82 are mounted on the radiating pipes closely below the slits 74 and 75, these cover plates 82 overlapping each other like scales.

I claim:

In a vacuum drying apparatus for drying materials by heat radiation comprising walls defining a vacuum chamber, a horizontal belt conveyor in said chamber, means for feeding material to be dried to the upper run of said belt conveyor for transportation thereacross, means for removing materials from said upper run, and a plurality of U-shaped heating ducts having vertical and horizontal portions, said horizontal portions being spaced above and parallel to the upper run of said conveyor, the improvement which comprises means defining slits through the upper portion of said chamber transverse to said horizontal portion of said U-shaped ducts, overlapping, staggered, spaced-apart multiple plate means positioned directly below and in close adjacency to said slits in order to prevent the downward deposit of extraneous matter onto said belt conveyor, box means positioned in gastight contact around the edges of said slits with the vertical portions of said U-shaped ducts extending up through said box means in spaced relation to the walls thereof and passing in gas-tight contact through the top thereof, stiffening means positioned along the vertical length of said box means between the vertical portions of said U-shaped ducts extending through said box means, and screen means positioned around the vertical portions of said U-shaped ducts extending through said box means to protect said box means from becoming overheated by heat radiating from said ducts.

References Cited in the file of this patent UNITED STATES PATENTS 30,436 Tourne Oct. 16, 1860 1,813,613 Eslava July 7, 1931 2,115,769 Harris May 3, 1938 FOREIGN PATENTS 833,178 France Mar. 15, 1943 OTHER REFERENCES A Method for the Production of Dry Powdered Orange Juice, by J. C. Sluder et al., Food Technology. vol. 1, No. 1, January 1947, pages 85 to 93 relied on. 

